PRD2009-10 Proposed Registration Decision Verticillium albo-atrum strain WCS850 (publié aussi en français) 20 August 2009 This document is published by the Health Can ada Pest Management Regulatory Agency. For further information, please contact: Publications Internet: pmra_publications@hc-sc.gc.ca Pest Management Regulatory Agency healthcanada.gc.ca/pmra Health Canada Facsimile: 613-736-3758 2720 Riverside Drive Information Service: A.L. 6605C 1-800-267-6315 or 613-736-3799 Ottawa, Ontario pmra_infoserv@hc-sc.gc.ca K1A 0K9
HC Pub: 8342 ISBN: 978-1-100-13121-4 (978-1-100-13122-1) Catalogue number: H113-9/2009-10E (H113-9/2009-10E-PDF) Her Majesty the Queen in Right of Canada, represented by the Minister of Health Canada, 2009 All rights reserved. No part of this information (publication or product) may be reproduced or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, or stored in a retrieval system, without prior written permission of the Minister of Public Works and Government Services Canada, Ottawa, Ontario K1A 0S5.
Table of Contents Overview...1 Proposed Registration Decision for Verticillium albo-atrum strain WCS850...1 What Does Health Canada Consider When Making a Registration Decision?...1 What Is Verticillium albo-atrum isolate WCS850?...2 Health Considerations...2 Environmental Considerations...4 Value Considerations...4 Measures to Minimize Risk...4 Next Steps...5 Other Information...5 Science Evaluation...7 1.0 The Active Ingredient, Its Properties and Uses...7 1.1 Identity of the Microbial Pest Control Agent...7 1.2 Physical and Chemical Properties of the Active Ingredient and End-Use Product...8 1.3 Directions for Use...8 1.4 Mode of Action...8 2.0 Methods of Analysis...9 2.1 Methods for Identification of the Microorganism...9 2.2 Methods for Establishment of Purity of Seed Stock...9 2.3 Methods to Define the Content of the Microorganism in the Manufactured Material Used for the Production of Formulated Products...10 2.4 Methods to Determine and Quantify Residues (Viable or Non-viable) of the Active Microorganism and Relevant Metabolites...10 2.5 Methods for Determination of Relevant Impurities in the Manufactured Material...10 2.6 Methods to Show Absence of Any Human and Mammalian Pathogens...10 2.7 Methods to Determine Storage Stability, Shelf-life of the Microorganism...10 3.0 Impact on Human and Animal Health...11 3.1 Toxicity and Infectivity Summary...11 3.2 Occupational/Bystander Exposure and Risk Assessment...13 3.2.1 Occupational...13 3.2.2 Bystander...13 3.3 Dietary Exposure and Risk Assessment...14 3.3.1 Food...14 3.3.2 Drinking Water...14 3.3.3 Acute and Chronic Dietary Risks for Sensitive Subpopulations...14 3.4 Maximum Residue Limits...15 3.5 Aggregate Exposure...15 3.6 Cumulative Effects...15 4.0 Impact on the Environment...15 4.1 Fate and Behaviour in the Environment...15 4.2 Effects on Non-Target Species...17 4.2.1 Effects on Terrestrial Organisms...17 4.2.2 Effects on Aquatic Organisms...18 Proposed Registration Decision PRD2009-10
5.0 Value...19 5.1 Effectiveness Against Pests...19 5.1.1 Acceptable Efficacy Claims...19 5.2 Phytotoxicity to Host/Non-Target Plants...20 5.3 Economics...20 5.4 Sustainability...20 5.4.1 Survey of Alternatives...20 5.4.2 Compatibility with Current Management Practices Including Integrated Pest Management...21 5.4.3 Information on the Occurrence or Possible Occurrence of the Development of Resistance...21 5.4.4 Contribution to Risk Reduction and Sustainability...21 6.0 Pest Control Product Policy Considerations...21 6.1 Toxic Substances Management Policy Considerations...21 6.2 Formulants and Contaminants of Health or Environmental Concern...22 7.0 Summary...22 7.1 Methods for Analysis of the Micro-organism as Manufactured...22 7.2 Human Health and Safety...22 7.3 Environmental Risk...23 7.4 Value...24 8.0 Proposed Regulatory Decision...24 List of Abbreviations...25 Appendix I Tables and Figures...27 Table 1 Toxicity and Infectivity of Verticillium albo-atrum strain WCS850...27 Table 2 Toxicity to Non-Target Species...29 Table 3 Alternative Active Ingredients Registered to Control Dutch Elm Disease...31 Table 4 Use (label) Claims Proposed by Applicant and Whether Acceptable or Unsupported...32 References...33 Proposed Registration Decision PRD2009-10
Overview Proposed Registration Decision for Verticillium albo-atrum strain WCS850 Health Canada s Pest Management Regulatory Agency (PMRA), under the authority of the Pest Control Products Act and Regulations, is proposing full registration for the sale and use of Verticillium isolate WCS850 and Dutch Trig, containing the microbial pest control agent Verticillium albo-atrum strain WCS850, to prevent Dutch elm disease in uninfected elm trees. An evaluation of available scientific information found that, under the approved conditions of use, the product has value and does not present an unacceptable risk to human health or the environment. This Overview describes the key points of the evaluation, while the Science Evaluation provides detailed technical information on the human health, environmental and value assessments of Verticillium isolate WCS850 and Dutch Trig. What Does Health Canada Consider When Making a Registration Decision? The key objective of the Pest Control Products Act is to prevent unacceptable risks to people and the environment from the use of pest control products. Health or environmental risk is considered acceptable 1 if there is reasonable certainty that no harm to human health, future generations or the environment will result from use or exposure to the product under its proposed conditions of registration. The Act also requires that products have value 2 when used according to the label directions. Conditions of registration may include special precautionary measures on the product label to further reduce risk. To reach its decisions, the PMRA applies modern, rigorous risk-assessment methods and policies. These methods consider the unique characteristics of sensitive subpopulations in humans (for example, children) as well as organisms in the environment (for example, those most sensitive to environmental contaminants). These methods and policies also consider the nature of the effects observed and the uncertainties when predicting the impact of pesticides. For more information on how the PMRA regulates pesticides, the assessment process and risk-reduction programs, please visit the Pesticides and Pest Management portion of Health Canada s website at healthcanada.gc.ca/pmra. 1 2 Acceptable risks as defined by subsection 2(2) of the Pest Control Products Act. Value as defined by subsection 2(1) of the Pest Control Products Act: the product s actual or potential contribution to pest management, taking into account its conditions or proposed conditions of registration, and includes the product s (a) efficacy; (b) effect on host organisms in connection with which it is intended to be used; and (c) health, safety and environmental benefits and social and economic impact. Page 1
Before making a final registration decision on Verticillium albo-atrum strain WCS850, the PMRA will consider all comments received from the public in response to this consultation document. 3 The PMRA will then publish a Registration Decision 4 on Verticillium albo-atrum strain WCS850, which will include the decision, the reasons for it, a summary of comments received on the proposed final registration decision and the PMRA s response to these comments. For more details on the information presented in this Overview, please refer to the Science Evaluation of this consultation document. What Is Verticillium albo-atrum isolate WCS850? Verticillium albo-atrum strain WCS850 is a microbial pest control agent (MPCA) used to prevent Dutch elm disease by inducing the treated tree s natural defense mechanisms, a process called induced systemic resistance. The end-use product, Dutch Trig, is a commercial fungicide product that contains Verticillium albo-atrum strain WCS850 as the active ingredient. Health Considerations Can Approved Uses of Verticillium albo-atrum strain WCS850 Affect Human Health? Verticillium albo-atrum strain WCS850 is unlikely to affect your health when Dutch Trig is used according to the label directions. When assessing health risks, several key factors are considered: the microorganism s biological properties (for example, production of toxic byproducts), reports of any adverse incidents, its potential to cause disease or toxicity as determined in toxicological studies and the level to which people may be exposed relative to exposures already encountered in nature to other isolates of this microorganism. Negligible exposure to Verticillium albo-atrum strain WCS850 is expected when handling and applying Dutch Trig. Dutch Trig is injected into trees using a completely closed application system and is packaged into thick polyethylene vials that are waterproof and virtually unbreakable. Toxicological studies in laboratory animals describe potential health effects from large doses in order to identify any potential pathogenicity, infectivity and toxicity concerns. When spores of Verticillium albo-atrum strain WCS850 were tested on laboratory animals, there were no signs that it caused any toxicity or disease. Furthermore, Verticillium albo-atrum strain WCS850 does not grow at temperatures above 30 C and few adverse effects to Verticillium spp. were reported in published scientific literature despite intensive research. 3 4 Consultation statement as required by subsection 28(2) of the Pest Control Products Act. Decision statement as required by subsection 28(5) of the Pest Control Products Act. Page 2
Residues in Water and Food Dietary risks from food and water are not of concern The Food and Drugs Act prohibits the sale of food containing a pesticide residue that exceeds the established maximum residue limit. Pesticide maximum residue limits are established for the Food and Drugs Act purposes through the evaluation of scientific data under the Pest Control Products Act. Each maximum residue limit value determines the maximum concentration in parts per million (ppm) of a pesticide allowed in or on certain foods. Food containing a pesticide residue that does not exceed the established maximum residue limit does not pose an unacceptable health risk. As there are no direct applications to food and no significant adverse effects were reported in Tier I acute toxicity/pathogenicity studies, the establishment of a maximum residue limit is not required for Verticillium albo-atrum strain WCS850 under section 4(d) of the Food and Drugs Act (adulteration of food) as defined under Division 15, section B.15.002 of the Food and Drugs Regulations. In addition, the likelihood of residues of Verticillium albo-atrum strain WCS850 contaminating drinking water supplies is negligible. Consequently, dietary exposure and risk are minimal to nonexistent Occupational Risks From Handling Dutch Trig Occupational risks are not of concern when Dutch Trig is used according to label directions, which include protective measures Workers using Dutch Trig are not likely to come into direct contact with Verticillium albo-atrum strain WCS850 during application. Dutch trig is injected into trees using a specialized injection tool which was designed to prevent spillage. Furthermore, Dutch Trig is packaged in thick polyethylene vials that are waterproof and virtually unbreakable. However, minimal worker exposure to Verticillium albo-atrum strain WCS850 may occur via the dermal route during routine maintenance of the injection equipment. To prevent exposure during application and maintenance of the injection equipment, the label will specify that anyone applying or maintaining injection equipment must wear waterproof gloves, long-sleeved shirts, long pants, and shoes plus socks. For bystanders, exposure is expected to be much less than that of handlers and applicators and is also considered negligible. Page 3
Environmental Considerations What Happens When Dutch Trig is Introduced Into the Environment? Environmental risks are not of concern Verticillium albo-atrum strain WCS850 is a natural un-pigmented (white) variant of Verticillium albo-atrum. Verticillium albo-atrum is a plant pathogen that can infect many different tree species and vegetable crops causing Verticillium wilt disease. Strain WCS850 differs from the pigmented wild type in that it has lost its ability to produce resting structures and thus has lost its ability to persist in its natural environment. Verticillium albo-atrum strain WCS850 has also lost much of its ability to infect plants. After Dutch Trig is injected into elm trees, Verticillium albo-atrum strain WCS850 is contained within a growth ring of the treated elm tree. The WCS850 strain is just pathogenic enough to induce a natural resistance response in the injected elm, but has lost so much of its pathogenicity that it is no longer capable of successfully infecting an elm with Verticillium wilt disease. After injection, Verticillium albo-atrum strain WCS850 can only be recovered from the injection site, and only up to two weeks after injection. The risk to terrestrial and aquatic organisms from the use of Dutch Trig is very low based on the negligible potential for environmental exposure. Value Considerations What Is the Value of Dutch Trig? Dutch Trig induces resistance in elm trees to fend off beetle-inflicted Dutch elm disease infections with its own natural defence mechanisms. Dutch Trig prevents Dutch elm disease in uninfected elms. The injection system is self contained consisting of virtually unbreakable plastic vials that can only be used in the Dutch Trig Tree Injection Tool. No mixing or diluting is required. Treatment with Dutch Trig causes no adverse effects on the tree and does not affect the beetle population or prevent beetles from feeding on elm trees. Dutch Trig can be used in the urban environment (streets, parks, backyards) on trees that provide aesthetic, environmental, economic and psychological benefits. Measures to Minimize Risk Labels of registered pesticide products include specific instructions for use. Directions include risk-reduction measures to protect human and environmental health. These directions must be followed by law. The PMRA is proposing key risk-reduction measures on the label of Dutch Trig to address the potential risks identified in this assessment. Page 4
Key Risk-Reduction Measures Human Health To prevent exposure to Verticillium albo-atrum strain WCS850 during application and during routine maintenance of the injection equipment, anyone applying Dutch Trig or maintaining injection equipment must wear waterproof gloves, long-sleeved shirts, long pants, and shoes plus socks. Environment As a general precaution, statements will be added to the label to prohibit handlers from contaminating aquatic habitats during routine maintenance of the injection system. Next Steps Before making a final registration decision on Verticillium albo-atrum strain WCS850, the PMRA will consider all comments received from the public in response to this consultation document. The PMRA will accept written comments on this proposal up to 45 days from the date of publication of this document. Please forward all comments to PMRA Publications. The PMRA will then publish a Registration Decision, which will include its decision, the reasons for it, a summary of comments received on the proposed final decision and the Agency s response to these comments. Other Information When the PMRA makes its registration decision, it will publish a Registration Decision on Verticillium albo-atrum strain WCS850 (based on the Science Evaluation of this consultation document). In addition, the test data referenced in this consultation document will be available for public inspection, upon application, in the PMRA s Reading Room (located in Ottawa). Page 5
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Science Evaluation Verticillium albo-atrum strain WCS850 1.0 The Active Ingredient, Its Properties and Uses 1.1 Identity of the Microbial Pest Control Agent Active microorganism Function Binomial name Verticillium albo-atrum strain WCS850 Prevent Dutch elm disease (Ophiostoma novo-ulmi) by inducing the treated tree s systemic resistance. Verticillium albo-atrum strain WCS850 Taxonomic designation Patent status information Minimum purity of active ingredient Kingdom Sub-kingdom Phylum Sub-phylum Class Sub-class Order Genus Species Strain Identity of relevant impurities of toxicological, environmental and/or significance Fungi Dikarya Ascomycota Pezizomycotina Sordariomycetes Sordariomycetes incertae sedis Phyllachorales Vertcillium albo-atrum WCS850 No patents are held by the applicant in Canada. 1.0 H 10 7 colony forming units (CFU)/mL The technical grade active ingredient does not contain any impurities or micro contaminants known to be Toxic Substances Management Policy (TSMP) Track 1 substances. The product must meet microbiological contaminants release standards. Verticillium alboatrum strain WCS850 does not produce any known toxins or any other known toxic metabolites. Page 7
1.2 Physical and Chemical Properties of the Active Ingredient and End-Use Product Technical Grade Active Ingredient Verticillium isolate WCS850 Property Result Physical state Aqueous suspension Guarantee 1.0 10 7 CFU/mL (nominal) Colour Clear Odour Odourless ph 7.0 Density 1 kg/l (bulk) End-Use Product Dutch Trig Property Result Physical state Aqueous suspension Guarantee 1.0 10 7 CFU/mL (nominal) Colour Clear Odour Odourless ph 7.0 Density 1 kg/l (bulk) 1.3 Directions for Use Dutch Trig will prevent beetle-vectored infection of healthy elm trees from Dutch elm disease (Ophiostoma ulmi, Ophiostoma novo-ulmi). Inject one drop from a 40 ml vial every 10 cm of tree circumference using the Dutch Trig tree inoculation tool at a comfortable waist height (refer to illustration on label). Application of Dutch Trig may only be executed with the Dutch Trig tree inoculation tool. Treatments should take place in early spring after bud break and before full leaf (at 50% leaf expansion). One treatment per year is required to protect elm trees from infection throughout the season. Only inject healthy elm trees which show no sign of Dutch elm disease as Dutch Trig has no curative properties. Dutch Trig is to be used on American elm trees only. Dutch Trig must be refrigerated prior to use. Detailed information on storing, transporting and applying Dutch Trig can be found on the product label. 1.4 Mode of Action Verticillium albo-atrum strain WCS850 is a variant that does not produce resting spores. Infection of elm trees with the organism induces a systemic acquired resistance (SAR) response. SAR is the activation of plant defences in uninfected parts of the plant which makes the entire plant more resistant to secondary infection. The response to this infection is localized at first and subsequently spreads systemically and develops in untreated parts of the tree. The effect is long lasting and often confers broad-based resistance to different pathogens. SAR acts non-specifically throughout the plant and reduces the severity of disease. Host resistance to Page 8
Dutch elm disease is associated with the ability of elms to localize infection by limiting the movement of the pathogen in the vascular system. 2.0 Methods of Analysis 2.1 Methods for Identification of the Microorganism The microbial pest control agent (MPCA) in Verticillium isolate WCS850 and Dutch Trig is a spontaneous hyaline (white) variant of Verticillium albo-atrum. The classical approach of using morphological characteristics in distinguishing this MPCA from a closely-related species, Verticillium dahliae, is inadequate because this hyaline strain lacks an important speciesdeterminant, i.e. the presence of microsclerotia or dauermycelium. Instead, DNA-based methods such as whole genome analysis by amplified fragment length polymorphism and single gene analysis of rdna-its (internal transcribed spacers) by species-specific PCR primers are required. In addition, Verticillium albo-atrum does not grow on Czapek Dox agar at 30 C whereas Verticillium dahliae still grows at 30 C, albeit at a reduced rate. Also, Verticillium alboatrum is incompatible in paired experiments with four reference isolates of Verticillium dahliae representing all four vegetative compatibility groups of this species. These methods, however, do not distinguish strain WCS850 from other hyaline strains of this species. 2.2 Methods for Establishment of Purity of Seed Stock The production stock of Verticillium albo-atrum strain WCS850 is maintained at the Central Bureau for Fungi (Centraalbureau voor Schimmelcultures or CBS), an internationally recognized culture collection located in the Netherlands. The methods and tests employed by CBS to ensure the integrity and purity of the MPCA are available through the European Union s Common Access to Biological Resources and Information (CABRI) consortium. These methods were developed for CABRI by the German Collection of Microorganisms and Cell Cultures (Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH or DSMZ), CBS and the Belgian Co- Ordinated Collections of Micro-Organisms. In short, cultures are maintained and preserved by cryopreservation (in or above liquid nitrogen, or at -70 C) or by freeze-drying (shelf freezedrying, spin freeze-drying, liquid freeze-drying or vacuum freeze-drying). In rare cases, microorganisms that cannot be preserved by one of the metabolically inactive methods above will be preserved as metabolically active cultures by periodic transfer on agar/liquid culture or as agar cultures under mineral oil. Irrespective of the applied preservation method, all preserved stocks are monitored for viability of the strains and the number of available ampoules, capillary tubes or straws. Cultures are also tested for purity and, when appropriate, the identity of the strain. Testing is performed immediately after each culture is preserved. Page 9
2.3 Methods to Define the Content of the Microorganism in the Manufactured Material Used for the Production of Formulated Products The guarantee of Dutch Trig is based on the number of viable spores per volume of product. The total spore count is determined by means of a hemacytometer. In addition, the germination rate of each batch must be greater or equal to 80%. 2.4 Methods to Determine and Quantify Residues (Viable or Non-viable) of the Active Microorganism and Relevant Metabolites No known toxins are produced by Verticillium albo-atrum despite intensive research on Verticillium spp. The mode of action of the MPCA does not involve any direct toxic interactions between the MPCA and the target pest, Ophiostoma novo-ulmi. Furthermore, the results of supporting mammalian toxicity and pathogenicity data do not indicate any toxic or pathogenic effects. Based on the above information and the proposed use of Dutch Trig in elm trees, the establishment of a maximum residue limit (MRL) is not required for Verticillium albo-atrum strain WCS850 under section 4(d) of the Food and Drugs Act (adulteration of food) as defined under Division 15, section B.15.002 of the Food and Drugs Regulations. As a result, no methods to determine and quantify the MPCA and relevant metabolites are required. 2.5 Methods for Determination of Relevant Impurities in the Manufactured Material The quality control procedures used to limit contaminating microorganisms during manufacture of Verticillium isolate WCS850 and Dutch Trig are acceptable. Batches showing microbial contamination are discarded. 2.6 Methods to Show Absence of Any Human and Mammalian Pathogens As noted in Section 2.5, quality control procedures are used to limit microbial contamination in Verticillium albo-atrum strain WCS850 and Dutch Trig. These procedures include contamination checks to detect contaminating microbial contamination. Acceptable microbial contaminant analysis data were submitted for five batches of Dutch Trig. 2.7 Methods to Determine Storage Stability, Shelf-life of the Microorganism The viability of Verticillium albo-atrum strain WCS850 in Dutch Trig was evaluated over a 10-week period at 4 C. The submitted storage stability data support a storage period for Dutch Trig of 10 weeks at 4 C. Page 10
3.0 Impact on Human and Animal Health 3.1 Toxicity and Infectivity Summary The PMRA conducted a detailed review of the toxicological database for Verticillium alboatrum strain WCS850 in Verticillium isolate WCS850 (technical grade active ingredient) and Dutch Trig. The database is considered complete, consisting of published literature, scientific rationales and a laboratory animal (in vivo) infectivity study (intraperitoneal infectivity) that was carried out in accordance with currently accepted international testing protocols and good laboratory practices. Waiver requests were deemed acceptable to address all remaining health data requirements (i.e. acute oral toxicity/infectivity, acute pulmonary toxicity/infectivity, acute dermal toxicity and dermal irritation). The scientific quality of the information and data is high, and the database is considered sufficient to characterize the infectivity of this pest control agent and product. In an acute intraperitoneal infectivity study, a group of 8-week old Sprague Dawley rats (3 per sex) were injected with Dutch Trig (containing approximately 9.1 10 6 CFU/ ml) at a dose of approximately 1.7 10 7 CFU per animal. Animals were then observed for up to 14 days. An untreated control group (2 per sex) was also included in the study protocol. In this study, Verticillium albo-atrum strain WCS850 was not pathogenic to rats. No adverse effects were observed in any of the test animals and no gross findings were reported at necropsy. This intraperitoneal infectivity study is classified as acceptable and satisfies the guideline requirement for an intraperitoneal infectivity study in the rat. Requests to waive all other health requirements were accepted based on the biological properties of the MPCA, the nature of the end-use formulation and the proposed use pattern of Dutch Trig. Verticillium spp. are cosmopolitan fungi found in soil and on crop debris left in the soil after harvest. These fungi have a very wide host range on plants, and have been studied in depth because of their important economic impact on agricultural crops. Verticillium albo-atrum occurs generally amongst many food crops and plants including potato and tomato. Given these fungi are so common, both people and animals have likely come in contact with them when handling earth, plants, crop residues or dead organic material. Despite the extensive research and the likely exposure, there are only few reports of potential adverse effects in published scientific literature. Only two references to human or animal pathogenicity of Verticillium can be found in published scientific literature. In one case, peritonitis was reported in a patient undergoing peritoneal dialysis while in the other case, fungal peritonitis was preceded by at least one episode of bacterial peritonitis. The ability of Verticillium albo-atrum strain WCS850 to grow and colonize warm-blooded mammals is doubtful as it does not grow at temperatures above 30 C. In addition, Verticillium species are not known to produce toxins or toxic metabolic by-products. A search of published scientific literature has yielded only one obscure citation which reported the production of thiourea by Verticillium albo-atrum. This report was published in 1940, and no other such reports were found in more recent scientific publications. Also, the MPCA is not related to any known toxigenic human pathogen. Page 11
Verticillium albo-atrum is not known to express any specific sensitizing compounds. However, one report of an allergenic response was reported in combination with the presence of Verticillium albo-atrum in greenhouse workers. This publication, however, did not provide any evidence to support Verticillium albo-atrum being the causal organism. During spore sampling, Penicillium, Cladosporium and Cephalosporium were the predominant fungi found in the greenhouse. Verticillium was also found in lower concentrations as well as Aspergillus fumigatus. No other reports of allergic responses to Verticillium were found in published scientific literature. The applicant also noted that none of the employees involved in the production of Dutch Trig have ever showed any symptoms of sensitization or allergic responses since production began in 1992. In addition, none of the commercial arborists have ever displayed any dermal or allergic effects from applying Dutch Trig to over 450 000 elms in the Netherlands. The PMRA, however, considers all MPCAs to be potential sensitizers by default. Verticillium albo-atrum strain WCS850 in Dutch Trig is used to induce systemic resistance in elm trees to protect them against Dutch elm disease. This mode of action does not involve any pathogenicity, toxicity or any other direct interaction between the target pest, Ophiostoma novo-ulni, and the MPCA. Instead, the mode of action of Verticillium albo-atrum strain WCS850 relies completely on the exact level of pathogenicity that it has on elm trees. The key to the success of the MPCA is that it is just pathogenic enough to induce a natural resistance in the injected elm, but has lost so much of its pathogenicity that it is no longer capable of successfully infecting an elm with Verticillium wilt. To be efficacious, Dutch Trig must be injected in elm trees by trained personnel. The product is shipped in sealed virtually unbreakable vials and it is injected using a closed injection system. This closed injection system prevents spills and data show the injected MPCA is contained in the annual growth ring of treated trees. As a consequence, negligible occupational and bystander exposure are expected from the proposed use of Verticillium albo-atrum strain WCS850. Higher tier subchronic and chronic toxicity studies were not required because of the low acute toxicity of the test substance, and no indications of infectivity, toxicity or pathogenicity in the test animals treated in the Tier I acute oral and pulmonary toxicity/infectivity tests. Within the available scientific literature, there are no reports that suggest Verticillium albo-atrum strain WCS850 has the potential to cause adverse effects on the endocrine system of animals. The submitted toxicity/infectivity studies in the rodent indicate that, following oral and pulmonary routes of exposure, the immune system is still intact and able to process and clear the spores of Verticillium albo-atrum strain WCS850. Based on the weight of evidence of available data, no adverse effects to the endocrine or immune systems are anticipated for Verticillium albo-atrum strain WCS850. Page 12
3.2 Occupational/Bystander Exposure and Risk Assessment 3.2.1 Occupational Negligible worker exposure to Verticillium albo-atrum strain WCS850 is expected when Dutch Trig is applied according to the label instructions. The end-use product is shipped in sealed virtually unbreakable vials and it is injected into elm trees by trained personnel using a closed injection system. This closed injection system greatly reduces all potential routes of exposure during application. Worker exposure to Verticillium albo-atrum strain WCS850, however, may occur via the dermal route during routine maintenance of the injection equipment. Given unbroken skin is a natural barrier to microbial invasion of the human body, dermal absorption could occur only if the skin were cut, if the microbe were a pathogen equipped with mechanisms for entry through or infection of the skin, or if metabolites were produced that could be dermally absorbed. This MPCA has not been identified as a wound pathogen and there is no indication that it could penetrate intact skin of healthy individuals. Exposure to workers during routine maintenance is expected to be low. To prevent exposure during application and during maintenance of the injection equipment, the label will specify that anyone applying or maintaining injection equipment must wear waterproof gloves, long-sleeved shirts, long pants, and shoes plus socks. The PMRA assumes that all microorganisms contain substances that can elicit allergic reactions upon repeated exposure to any microbial organism. For Verticillium albo-atrum strain WCS850, however, no additional label restrictions or risk mitigation measures are necessary to protect workers. Repeated exposures to this MPCA are not likely to occur since the product is injected into elm trees by trained personnel using a closed injection system. 3.2.2 Bystander Overall the PMRA does not expect that bystander exposures will pose an undue risk on the basis of the low toxicity/pathogenicity profile for the spores of Verticillium albo-atrum strain WCS850 and the negligible exposure to bystanders from the use of Dutch Trig. The label does allow applications to trees located in residential and recreational areas; however, Verticillium albo-atrum strain WCS850 is contained within a growth ring of the treated elm trees. Data were submitted which showed that, following injection, Verticillium albo-atrum strain WCS850 can only be re-isolated from the wood of the treated elm at the site of injection, and only up until two weeks after treatment. After treatment, the treated elm rapidly identifies the infection with Verticillium albo-atrum strain WCS850 in its vascular system and uses its natural defense mechanisms to rid its vascular system of this infection. Non-occupational exposure and risks to adults, infants and children are low. Furthermore, exposure to infants and children in school, residential and daycare facilities is likely to be minimal to non-existent. Consequently, the health risk to infants and children is expected to be negligible. Page 13
3.3 Dietary Exposure and Risk Assessment 3.3.1 Food Dutch Trig is to be injected in elm trees to prevent Dutch elm disease. Negligible to no risk is expected for the general population, including infants and children, or animals because there are no direct applications of Dutch Trig to food or feed crops. Therefore, there is no concern for chronic risks posed by dietary exposure of the general population and sensitive subpopulations, such as infants and children. 3.3.2 Drinking Water No risks are expected from exposure to this microorganism via drinking water because exposure will be negligible. The label instructs users not to contaminate irrigation or drinking water supplies or aquatic habitats by cleaning of equipment or disposal of wastes. Furthermore, runoff from treated trees is not expected and therefore it is unlikely that Verticillium albo-atrum strain WCS850 will enter aquatic environments. Moreover, the MPCA is not expected to proliferate in aquatic habitats and percolation through soil and municipal treatment of drinking water would reduce the possibility of significant transfer of Verticillium albo-atrum strain WCS850 or its residues to drinking water. Therefore, potential exposure to Verticillium albo-atrum strain WCS850 in surface and drinking water is negligible. 3.3.3 Acute and Chronic Dietary Risks for Sensitive Subpopulations Calculation of acute reference doses and acceptable daily intakes are not usually possible for predicting acute and long term effects of microbial agents in the general population or to potentially sensitive subpopulations, particularly infants and children. The single (maximum hazard) dose approach to testing MPCAs is sufficient for conducting a reasonable general assessment of risk if no significant adverse effects (i.e. no acute toxicity, infectivity or pathogenicity endpoints of concern) are noted in acute toxicity and infectivity tests. Based on all the available information and hazard data, the PMRA concludes that the spores of Verticillium albo-atrum strain WCS850 are of low toxicity, are not pathogenic or infective to mammals, and that infants and children are likely to be no more sensitive to the MPCA than the general population. Thus there are no threshold effects of concern and, as a result, no need to require definitive (multiple dose) testing or apply uncertainty factors to account for intraspecies and interspecies variability, safety factors or margins of exposure. Further factoring of consumption patterns among infants and children, special susceptibility in these subpopulations to the effects of the MPCA, including neurological effects from prenatal or postnatal exposures, and cumulative effects on infants and children of the MPCA and other registered micro-organisms that have a common mechanism of toxicity, do not apply to this MPCA. As a result, the PMRA has not used a margin of exposure (safety) approach to assess the risks of Verticillium alboatrum strain WCS850 to human health. Page 14
3.4 Maximum Residue Limits As there are no applications to food, the establishment of an MRL is not required for Verticillium albo-atrum strain WCS850 under section 4(d) of the Food and Drugs Act (adulteration of food) as defined under Division 15, section B.15.002 of the Food and Drugs Regulations. The Food and Drugs Act prohibits the sale of adulterated food, that is, food containing a pesticide residue that exceeds the established MRL. Pesticide MRLs are established for Food and Drugs Act purposes through the evaluation of scientific data under the Pest Control Products Act. Each MRL value defines the maximum concentration in parts per million (ppm) of a pesticide allowed in/on certain foods. Food containing a pesticide residue that does not exceed the established MRL does not pose an unacceptable health risk. 3.5 Aggregate Exposure Based on the toxicity and infectivity test data submitted and other relevant information, there is reasonable certainty no harm will result from aggregate exposure of residues of Verticillium albo-atrum strain WCS850 to the general Canadian population, including infants and children, when the microbial pest control product is used as labelled. This includes all anticipated dietary (food and drinking water) exposures and all other non-occupational exposures (dermal and inhalation) for which there is reliable information. Given Dutch Trig is to be injected in elm trees, dermal and inhalation exposure to the general public will be very low. Furthermore, few adverse effects from exposure to natural populations of Verticillium spp. in the environment have been reported. Even if there is an increase in exposure to this microorganism from the use of Dutch Trig there should not be any increase in potential human health risk. 3.6 Cumulative Effects The PMRA has considered available information on the cumulative effects of such residues and other substances that have a common mechanism of toxicity. These considerations included the cumulative effects on infants and children of such residues and other substances with a common mechanism of toxicity. Besides naturally occurring strains of Verticillium albo-atrum in the environment, the PMRA is not aware of any other microorganisms or other substances that share a common mechanism of toxicity with this active ingredient. No cumulative effects are anticipated if the residues of Verticillium albo-atrum strain WCS850 interact with related strains of this microbial species. 4.0 Impact on the Environment 4.1 Fate and Behaviour in the Environment Environmental fate testing is intended to demonstrate whether a MPCA is capable of surviving or replicating in the environment to which it is applied, and could provide an indication of which non-target organisms may be exposed to the MPCA as well as provide an indication of the extent Page 15
of exposure. Environmental fate data (Tier II/III) are not normally required at Tier I and are only triggered if significant toxicological effects in non-target organisms are noted in Tier I testing. For Verticillium albo-atrum strain WCS850, data and information were submitted on the biological and ecological characteristics of parent (pigmented) Verticillium albo-atrum as well as results of re-isolation attempts from treated elm trees. Verticillium albo-atrum is a plant pathogen that can infect many different plant species causing Verticillium wilt. This disease is considered a cool-weather disease because growth of Verticillium albo-atrum is optimal at approximately 21 C and is halted at temperatures below 10 C and at 30 C and higher. Verticillium albo-atrum strain WCS850 is a natural hyaline mutant of Verticillium albo-atrum. It differs significantly from the wild type strains because it has lost the ability to produce resting structures. With the loss of its capacity to produce resting structures, Verticillium albo-atrum strain WCS850 has lost its ability to persist in soil and crop residues. Hyaline strains of Verticillium albo-atrum are also generally regarded as less pathogenic than wild type strains and the mutation is irreversible. Studies were conducted in the Netherlands and in the United States to assess the location and life-span of Verticillium albo-atrum strain WCS850 in elm trees following treatment with Dutch Trig. These studies concluded that Verticillium albo-atrum strain WCS850 could be re-isolated from wood samples obtained approximately 5 10 cm (2 4 inches) above the site of injection, but only up to two weeks following injection. After removing the bark, a light grayish-brown discolouration of the vessels indicated the presence of Verticillium. At the end of the growing season this discolouration could no longer be found. The studies also concluded that spores were not transported throughout the entire crown by the inoculated xylem vessels because upward transport is halted when the xylem vessel is pierced upon injection at least until the damaged vessels are restored. After treatment, the elm tree apparently identifies the infection in its vascular system and uses its natural defence mechanisms to rid its vascular system of this infection. The injected Verticillium albo-atrum strain WCS850 is contained (compartmentalized) within one growth-ring (one growing season) in the elm. If the MPCA would ever be accidentally released into a suitable environment, strain WCS850 would not likely survive because it has lost the ability to produce resting mycelia necessary for survival. Also, Verticillium albo-atrum strain WCS850 would not likely be able to compete with wild type strains of Verticillium albo-atrum. The ability of Verticillium albo-atrum to grow and establish itself in water is not known; however, this species is not generally considered a water-borne fungus. Page 16
4.2 Effects on Non-Target Species 4.2.1 Effects on Terrestrial Organisms A study was submitted to address the effects of Verticillium albo-atrum strain WCS850 to terrestrial plants. In this study, the phytopathogenic effects of Verticillium albo-atrum strain WCS850 were evaluated over a period of 16 weeks after Dutch Trig was injected into various tree species, including Acer macrophyllum, Acer saccharum, Aesculus hippocastanum, Betula papyrifera, Castanea spp., Cornus nuttallii, Crataegus monogyna, Fagus spp., Magnolia spp., Malus spp., Prunus lusitanica, Prunus serrata, Quercus rubra, Rhododendron spp., Sorbus aucuparia, Ulmus carpinifolia, Ulmus leavis, Ulmus pumila, and Viburnum spp. Trees were injected in mid-may 2001 in accordance with a USEPA-issued experimental use permit; however, few details were reported in the study. Untreated trees, when available, were selected and served as negative controls. No phytopathogenic (wilting) or phytotoxic effects were noted throughout the study period even though Vertcillium-susceptible species (A. macrophyllum) were included in the study. The study was judged supplemental due to missing information. A replacement study, however, will not be required because non-target plant exposure is expected to be negligible based on the proposed use of Dutch Trig (discussed in greater detail below). In addition to the above non-target terrestrial plant study, several scientific rationales were submitted to waive testing on birds, mammals, arthropods, non-arthropod invertebrates and microorganisms based on the biological and ecological properties of the MPCA, the limited potential for exposure from the use of Dutch Trig and the nature of the end-use formulation. Verticillium albo-atrum is a ubiquitous soil-borne fungus with a wide geographical distribution, predominantly in temperate regions. Verticillium albo-atrum is known to have a northern distribution in North America and Europe, preferring temperate climates. It is known as a strictly root inhibiting fungus, able to cause wilting symptoms in a wide array of mostly vegetable crops and some susceptible tree species in specific circumstances. As a result, this species has been extensively studied. Despite this extensive research and the organism s ubiquitous nature, no adverse effects to birds, wild mammals, arthropods, non-arthropod invertebrates and microorganisms are attributed to Verticillium albo-atrum in published scientific literature. The original parent culture, from which Verticillium albo-atrum strain WCS850 was obtained, was isolated from a diseased potato field in the Netherlands. This strain of Verticillium albo-atrum is therefore regarded as indigenous to Northern Europe. As previously noted, Verticillium albo-atrum strain WCS850 is a natural hyaline mutant of the wild type Verticillium albo-atrum. This strain has lost its ability to produce resting structures and is generally regarded as less pathogenic than the wild type strain. As a result, Verticillium albo-atrum strain WCS850 has likely lost its ability to persist in its natural environment and to compete with wild type strains of Verticillium albo-atrum. In addition, strain WCS850 does not grow at temperatures of 30 C or higher. Page 17
The proposed use of Verticillium albo-atrum strain WCS850 is expected to yield negligible environmental exposure. Dutch Trig is directly injected by trained personnel into the xylem tissues of the healthy elm trees in spring, just after bud break. These injections are made with a closed injection system that limits environmental exposure by preventing spills of the formulated product. Following treatment with Dutch Trig, Verticillium albo-atrum strain WCS850 is quickly identified and eradicated by the treated elm tree through the use of its natural defence mechanism. The injected MPCA is thus contained (compartmentalized) within one growth-ring in the elm and is not released into the surrounding environment. The re-isolation of Verticillium albo-atrum strain WCS850 from the treated elms was demonstrated in a study, but this re-isolation was only possible from wood obtained at the site of injection, and only up until two weeks after treatment. The extent of potential environmental exposure is also further reduced by the packaging of the product, i.e. Dutch Trig is transported and shipped in virtually unbreakable vials with a maximum content of 40 ml. Even if the MPCA would ever be accidentally released into the environment, the impact, if any, would be temporary because Verticillium albo-atrum strain WCS850 has virtually no chances of survival because it can t produce the black resting structures that are necessary for long-term survival. Verticillium albo-atrum strain WCS850 would also have to cope with competition with wild type strains of Verticillium albo-atrum, which are more pathogenic to plants. The purpose of the Dutch Trig injections is to induce a natural phenomenon in trees known as systemic acquired resistance, a mechanism used by plants to defend themselves from various diseases. This treatment is analogous to human vaccinations. This type of resistance can be induced by inoculating or injecting plants with specific microorganisms which are just sufficiently pathogenic to initiate the tree s defense mechanisms, but are no longer capable of establishing disease. For Dutch Trig, the intent is to reinforce the elm s own natural defence mechanism against a possible Dutch elm disease infection later in the growing season. The mode of action of Verticillium albo-atrum strain WCS850 does not rely on any toxin or toxic metabolite interaction between MPCA and targeted Dutch elm disease organism, Ophiostoma novo-ulmi. Moreover, no report of Verticillium albo-atrum producing any type of toxin or toxic metabolite was found in published scientific. Based on all the available data and information on the effects of Verticillium albo-atrum strain WCS850 to non-target terrestrial organisms, there is reasonable certainty that no harm will be caused to birds, wild mammals, arthropods, non-arthropod invertebrates, microorganisms and plants from the use of Dutch Trig. 4.2.2 Effects on Aquatic Organisms No studies were submitted to address the hazards of Verticillium albo-atrum strain WCS850 to non-target aquatic organisms. Instead, scientific rationales were submitted to waive testing on fish, aquatic arthropods, aquatic arthropod invertebrates and aquatic plants. These rationales were also based on the biological and ecological properties of the MPCA, the limited potential for exposure from the use of Dutch Trig, and the nature of the end-use formulation. Page 18
No adverse effect to aquatic organisms or report of any kind of toxic metabolite was found in the published scientific literature. The ability of Verticillium albo-atrum to grow and establish itself in water is not known; however, this species is not generally considered a water-borne fungus. As noted in Section 4.2.1, negligible environmental exposure, including aquatic exposure, are expected from the proposed use of Dutch Trig in elm trees. Also, even if Verticillium albo-atrum strain WCS850 would ever be accidentally released into the environment, the impact, if any, would be temporary because it has largely lost its ability to persist in the environment and to compete with wild type strains of Verticillium albo-atrum. Based on all the available data and information on the effects of Verticillium albo-atrum strain WCS850 to aquatic organisms, there is reasonable certainty that no harm will be caused to non-target aquatic organisms from the use of Dutch Trig. As a precaution, standard label statements will prohibit handlers from contaminating aquatic habitats during application and routine maintenance of the injection system. 5.0 Value 5.1 Effectiveness Against Pests 5.1.1 Acceptable Efficacy Claims Greenhouse trials were conducted at the University of Wisconsin in 2001. Two year old cloned ramets (grown in a greenhouse) with differing levels of natural resistance were tested. Treatment with Dutch Trig prior to Dutch elm disease infection showed less discolouration under the bark, less discolouration on the cross sections and no wilting in the leaves when compared to the Dutch elm disease control treatments. There seems to be positive correlation between the tree s natural level of resistance and the induced level of protection after treatment. Therefore, the clones with a high level of natural resistance benefit most from the Dutch Trig treatment. Field trials were conducted in the Netherlands between 1990 and 2000. Mature trees of the same species, cultivar, size and location were included in the study. Application timing varied to determine the optimum timing of treatment, duration of treatment effects and activity of Dutch Trig against multiple infections in a single season (to simulate multiple beetle infestations). Dutch Trig was found to reduce disease incidence throughout the season and activity was independent of the timing or number of Dutch elm disease infections. The effects of the treatment were less effective in the second year. Therefore, applications should be made each spring. Applications made too early in the season failed to protect against infection, therefore treatment must occur when the trees start to leaf out. Dutch Trig treatment was effective against both Dutch elm disease pathogens (Ophiostoma ulmi, Ophiostoma novo-ulmi). Page 19